Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds little behavioral context beyond identifying JSDelivr as the source; it does not mention data freshness, rate limits, or response structure, but this is acceptable given the annotation coverage.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, focused sentence with no fluff. It clearly front-loads the core function without any unnecessary words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple, with all three parameters optional and well-documented in the schema, plus an output schema is present. The description provides essential context (JSDelivr leaderboard) and is complete enough for straightforward use, though it could benefit from an explicit verb or a hint about ordering.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema provides descriptions for 'by' and 'limit' (67% coverage), including allowed values and defaults. The description does not add any parameter details beyond what the schema already offers, so the baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the tool as returning a JSDelivr leaderboard of top-served npm packages. It specifies the resource (npm packages) and the source (JSDelivr), distinguishing it from sibling tools like npm_package_stats or list_npm_versions.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for retrieving a leaderboard of top npm packages, but it provides no explicit guidance on when to use it versus alternatives. No alternative tools or exclusions are mentioned, so usage context is only implied.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.